> semi-crappy indicator … good enough.

Agree. Another example of this is for metrics as percentiles per host that you have to average, vs histograms per host that get percentile calculated at aggregation time among hosts. Sure an avg/max of a percentile is technically not a percentile, but in practice switching between one or the other hasn’t affected my operations at all. Yet I know some people are adamant about mathematical correctness as if that translates to operations.

That works ok when you have evenly distributed load (which you want / would hope to have), much less so when your workload is highly unbalanced.